A surgical operation such as a brain surgical operation and heart surgical operation is performed with an affected part being observed by an operator through an operating microscope. Accordingly, the operator strains his/her nerve because of very minute operation, and in many cases much time is spent for the operation. Such a long operating time will undesirably cause an increase in physical and mental fatigues of both the subject and the operator.
A medical optical equipment such as an operating microscope plays a very important role in such a high-level operation, and easiness of use of the medical optical equipment directly follows a reduction in the operating time. A conventional stand apparatus for permitting the medical optical equipment to be easily used is shown in FIGS. 10 and 11, for example (see Japanese Patent Laid-open No. Sho 56-32110 and corresponding U.S. Pat. No. 4,339,100).
Referring to FIG. 10, reference numerals 1 and 2 denote a base and a stand, respectively. The stand 2 is rotatable about a vertical axis .alpha. of rotation relative to the base 1. An electromagnetic clutch C is provided between the stand 2 and the base 1 to lock a rotational position of the stand 2 relative to the base 1. The base 1 is provided on its lower surface with casters 3 each having a locking mechanism and a vertically moving mechanism, thereby permitting the base 1 to be moved on an upper surface of a floor F and further permitting the base 1 to be locked at a desired position and to be adjusted in levelness.
A first parallel linkage 4 is pivotally mounted through a fulcrum 5 to an upper end portion of the stand 2. The first parallel linkage 4 is rotatable about the fulcrum 5 in a frontward direction (a direction shown by an arrow A) or in a rearward direction (a direction shown by an arrow B), and can be locked by an electromagnetic clutch (not shown) provided at the fulcrum 5. An upper end of the first parallel linkage 4 is formed by a horizontal shaft 6, and a second parallel linkage 7 and a third parallel linkage 8 are interlockingly mounted to the horizontal shaft 6. A front end of the third parallel linkage 8 is formed by a front link 9 extended downwardly, and an operating microscope 10 is mounted to a lower end of the front link 9.
The operating microscope 10 is located below an extension L of the horizontal shaft 6. Accordingly, the operating microscope 10 itself functions as a kind of weight to form a balancing structure like a so-called "yajirobei (balancing toy)", and the operating microscope 10 is swingable about an intersection 11 between the extension L and the front link 9, so that an operator can arbitrarily change an observation angle of the operating microscope 10 to observe an opened portion of the head of a subject 12. Further, electromagnetic clutches (not shown)provided at joint shafts 13 for joining the parallel linkage 7 to the horizontal shaft 6, thereby locking the swing position of the operating microscope 10 after changing the observation angle.
In such a conventional stand apparatus for a medical optical equipment, however, the front link 9 is swung about the intersection 11 in concert with the change in the observation angle of the operating microscope 10 by the operator 14 as shown in FIG. 11. Accordingly, there is a possibility that the front link 9 may strike against an assistant 15 present near the operator 14. Further, depending upon the observation angle, the front link 9 may strike against the operator 14 himself/herself. Thus, the operability of the stand apparatus is bad. Further, as the front link 9 itself has not been perfectly sterilized, the touch of the front link 9 with the operator 14 or the like is undesirable from a sanitary view. Further, the location of the stand apparatus of this kind is selected to an optimum position according to the content of the operation to be performed. That is, while a specific position in the periphery of the subject 12 is selected by indication from the operator 14, the work of moving the stand apparatus to the specific position and setting it at this position is carried out by a person not taking part in the operation because of sanitary demand. After moving the stand apparatus to the indicated position and then locking it, this person must carry out horizontal adjustment of the stand apparatus to make it perfectly horizontal. That is, since the floor F of an operating room is not perfectly horizontal, such horizontal adjustment is required. If the horizontal adjustment is not carried out, the vertical axis .alpha. becomes inclined. As a result, at the instance the electromagnetic clutch C is disengaged, the stand 2 and the structure thereabove possibly start largely rotating about the vertical axis .alpha.. In this manner, every time the position of the stand apparatus in the prior art is changed, the horizontal adjustment must be carried out at the position after changed. Thus, the stand apparatus in the prior art is very troublesome to handle.
This invention has been achieved in view of the problems mentioned above, and it is an object of the present invention to provide a stand apparatus for a medical optical equipment which can prevent a link member supporting the medical optical equipment from largely swinging during operation of the equipment and eliminate the need of the horizontal adjustment.